The present invention relates to improvements in waste treatment and water recycling toilet systems, particularly to systems of the general type shown in U.S. Pat. No. 3,950,249, dated Apr. 13, 1976 and U.S. Pat. No. 4,210,528, dated July 1, 1980 both of which are assigned to the assignee of this application. Municipal-type sewage treatment systems, such as shown in U.S. Pat. Nos. 3,953,327 and 3,964,998, which are commonly referred to as "flow through systems", also have some pertinence to the present invention.
U.S. Pat. No. 3,964,998 shows that it has been known to biologically lower the organic compound concentration in the sewage by treatment for the sewage under anoxic conditions followed by treatment under aerobic conditions. This sequence has been advantageous in that bacteria in the anoxic reactor utilize organics in the sewage to accomplish the breakdown of nitrates, thus requiring no addition of a supplemental organic source into the system. However, such a flow through system requires removal of sludge, thus creating the problem of sludge transport and disposal. Also, in a flow-through system, some of the nitrates resulting from the treatment process flow out of the system and are thus not available for the treatment of organics at the anoxic stage. As a result, the organic load on the aerobic stage is increased, thus requiring a system with a large size aerobic stage.
Closed loop systems in the past have been advantageous in that no external water supply is needed, thus minimizing the unnecessary usage of potable water. Difficulties have arisen, however, out of deficiencies in the biological process of these systems. As a result of these deficiencies, inadequate treatment of wastes often resulted in the production of obnoxious odors and colors in the flush water and a rapid accumulation of biological solids in the system.
The closed loop system disclosed in U.S. Pat. No. 4,210,528 provided a system having effective management of nitrogen in the system so that it could be made of reasonable size, avoid undesirable odors and slow the build-up of solids.
It is an object of the present invention to provide an improved management of nitrogen to increase the efficiency of the system.